Enhancing security level against potential internal eavesdroppers in Non-Orthogonal Multiple Access (NOMA) has been reported as a serious challenge. In this letter, a novel secure NOMA scheme based on physical-layer security concepts is proposed. The proposed scheme exploits the random and independent channel characteristics to induce a different phase shift in each user’s symbol. Based on the assumption that the instantaneous channel phase between a user and the base station is available only at both ends, other users will not be able to decode the right symbol. Analytical and simulation average bit error rate performance results demonstrate the ability of the proposed scheme to degrade the performance at the eavesdropper without affecting the performance at other legitimate users and guarantee data confidentiality of each user.

中文翻译：

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一种针对未知内部窃听者的安全下行 NOMA 方案

据报道，在非正交多路访问 (NOMA) 中提高针对潜在内部窃听者的安全级别是一项严峻的挑战。在这封信中，提出了一种基于物理层安全概念的新型安全 NOMA 方案。所提出的方案利用随机和独立的信道特性在每个用户的符号中引起不同的相移。基于用户与基站之间的瞬时信道相位仅在两端可用的假设，其他用户将无法解码正确的符号。分析和模拟平均误码率性能结果证明了所提出的方案能够在不影响其他合法用户性能的情况下降低窃听者的性能并保证每个用户的数据机密性。